source3/lib/sharesec.c

   1 /*
   2  *  Unix SMB/Netbios implementation.
   3  *  SEC_DESC handling functions
   4  *  Copyright (C) Jeremy R. Allison            1995-2003.
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include "includes.h"
  21 #include "system/filesys.h"
  22 #include "../libcli/security/security.h"
  23 #include "../librpc/gen_ndr/ndr_security.h"
  24 #include "dbwrap.h"
  25
  26 /*******************************************************************
  27  Create the share security tdb.
  28  ********************************************************************/
  29
  30 static struct db_context *share_db; /* used for share security descriptors */
  31 #define SHARE_DATABASE_VERSION_V1 1
  32 #define SHARE_DATABASE_VERSION_V2 2 /* version id in little endian. */
  33 #define SHARE_DATABASE_VERSION_V3 3 /* canonicalized sharenames as lower case */
  34
  35 #define SHARE_SECURITY_DB_KEY_PREFIX_STR "SECDESC/"
  36 /* Map generic permissions to file object specific permissions */
  37
  38 extern const struct generic_mapping file_generic_mapping;
  39
  40 static int delete_fn(struct db_record *rec, void *priv)
  41 {
  42         rec->delete_rec(rec);
  43         return 0;
  44 }
  45
  46 /*****************************************************
  47  Looking for keys of the form: SHARE_SECURITY_DB_KEY_PREFIX_STR + "non lower case str".
  48  If we find one re-write it into a canonical case form.
  49 *****************************************************/
  50
  51 static int upgrade_v2_to_v3(struct db_record *rec, void *priv)
  52 {
  53         size_t prefix_len = strlen(SHARE_SECURITY_DB_KEY_PREFIX_STR);
  54         const char *servicename = NULL;
  55         char *c_servicename = NULL;
  56         char *newkey = NULL;
  57         bool *p_upgrade_ok = (bool *)priv;
  58         NTSTATUS status;
  59
  60         /* Is there space for a one character sharename ? */
  61         if (rec->key.dsize <= prefix_len+2) {
  62                 return 0;
  63         }
  64
  65         /* Does it start with the share key prefix ? */
  66         if (memcmp(rec->key.dptr, SHARE_SECURITY_DB_KEY_PREFIX_STR,
  67                         prefix_len) != 0) {
  68                 return 0;
  69         }
  70
  71         /* Is it a null terminated string as a key ? */
  72         if (rec->key.dptr[rec->key.dsize-1] != '\0') {
  73                 return 0;
  74         }
  75
  76         /* Bytes after the prefix are the sharename string. */
  77         servicename = (char *)&rec->key.dptr[prefix_len];
  78         c_servicename = canonicalize_servicename(talloc_tos(), servicename);
  79         if (!c_servicename) {
  80                 smb_panic("out of memory upgrading share security db from v2 -> v3");
  81         }
  82
  83         if (strcmp(servicename, c_servicename) == 0) {
  84                 /* Old and new names match. No canonicalization needed. */
  85                 TALLOC_FREE(c_servicename);
  86                 return 0;
  87         }
  88
  89         /* Oops. Need to canonicalize name, delete old then store new. */
  90         status = rec->delete_rec(rec);
  91         if (!NT_STATUS_IS_OK(status)) {
  92                 DEBUG(1, ("upgrade_v2_to_v3: Failed to delete secdesc for "
  93                           "%s: %s\n", rec->key.dptr, nt_errstr(status)));
  94                 TALLOC_FREE(c_servicename);
  95                 *p_upgrade_ok = false;
  96                 return -1;
  97         } else {
  98                 DEBUG(10, ("upgrade_v2_to_v3: deleted secdesc for "
  99                           "%s\n", rec->key.dptr ));
 100         }
 101
 102         if (!(newkey = talloc_asprintf(talloc_tos(),
 103                         SHARE_SECURITY_DB_KEY_PREFIX_STR "%s",
 104                         c_servicename))) {
 105                 smb_panic("out of memory upgrading share security db from v2 -> v3");
 106         }
 107
 108         status = dbwrap_store(share_db,
 109                                 string_term_tdb_data(newkey),
 110                                 rec->value,
 111                                 TDB_REPLACE);
 112
 113         if (!NT_STATUS_IS_OK(status)) {
 114                 DEBUG(1, ("upgrade_v2_to_v3: Failed to store secdesc for "
 115                           "%s: %s\n", c_servicename, nt_errstr(status)));
 116                 TALLOC_FREE(c_servicename);
 117                 TALLOC_FREE(newkey);
 118                 *p_upgrade_ok = false;
 119                 return -1;
 120         } else {
 121                 DEBUG(10, ("upgrade_v2_to_v3: stored secdesc for "
 122                           "%s\n", newkey ));
 123         }
 124
 125         TALLOC_FREE(newkey);
 126         TALLOC_FREE(c_servicename);
 127
 128         return 0;
 129 }
 130
 131 bool share_info_db_init(void)
 132 {
 133         const char *vstring = "INFO/version";
 134         int32 vers_id;
 135         int ret;
 136         bool upgrade_ok = true;
 137
 138         if (share_db != NULL) {
 139                 return True;
 140         }
 141
 142         share_db = db_open(NULL, state_path("share_info.tdb"), 0,
 143                                  TDB_DEFAULT, O_RDWR|O_CREAT, 0600);
 144         if (share_db == NULL) {
 145                 DEBUG(0,("Failed to open share info database %s (%s)\n",
 146                         state_path("share_info.tdb"), strerror(errno) ));
 147                 return False;
 148         }
 149
 150         vers_id = dbwrap_fetch_int32(share_db, vstring);
 151         if (vers_id == SHARE_DATABASE_VERSION_V3) {
 152                 return true;
 153         }
 154
 155         if (share_db->transaction_start(share_db) != 0) {
 156                 DEBUG(0, ("transaction_start failed\n"));
 157                 TALLOC_FREE(share_db);
 158                 return false;
 159         }
 160
 161         vers_id = dbwrap_fetch_int32(share_db, vstring);
 162         if (vers_id == SHARE_DATABASE_VERSION_V3) {
 163                 /*
 164                  * Race condition
 165                  */
 166                 if (share_db->transaction_cancel(share_db)) {
 167                         smb_panic("transaction_cancel failed");
 168                 }
 169                 return true;
 170         }
 171
 172         /* Move to at least V2. */
 173
 174         /* Cope with byte-reversed older versions of the db. */
 175         if ((vers_id == SHARE_DATABASE_VERSION_V1) || (IREV(vers_id) == SHARE_DATABASE_VERSION_V1)) {
 176                 /* Written on a bigendian machine with old fetch_int code. Save as le. */
 177
 178                 if (dbwrap_store_int32(share_db, vstring,
 179                                        SHARE_DATABASE_VERSION_V2) != 0) {
 180                         DEBUG(0, ("dbwrap_store_int32 failed\n"));
 181                         goto cancel;
 182                 }
 183                 vers_id = SHARE_DATABASE_VERSION_V2;
 184         }
 185
 186         if (vers_id != SHARE_DATABASE_VERSION_V2) {
 187                 ret = share_db->traverse(share_db, delete_fn, NULL);
 188                 if (ret < 0) {
 189                         DEBUG(0, ("traverse failed\n"));
 190                         goto cancel;
 191                 }
 192                 if (dbwrap_store_int32(share_db, vstring,
 193                                        SHARE_DATABASE_VERSION_V2) != 0) {
 194                         DEBUG(0, ("dbwrap_store_int32 failed\n"));
 195                         goto cancel;
 196                 }
 197         }
 198
 199         /* Finally upgrade to version 3, with canonicalized sharenames. */
 200
 201         ret = share_db->traverse(share_db, upgrade_v2_to_v3, &upgrade_ok);
 202         if (ret < 0 || upgrade_ok == false) {
 203                 DEBUG(0, ("traverse failed\n"));
 204                 goto cancel;
 205         }
 206         if (dbwrap_store_int32(share_db, vstring,
 207                                SHARE_DATABASE_VERSION_V3) != 0) {
 208                 DEBUG(0, ("dbwrap_store_int32 failed\n"));
 209                 goto cancel;
 210         }
 211
 212         if (share_db->transaction_commit(share_db) != 0) {
 213                 DEBUG(0, ("transaction_commit failed\n"));
 214                 return false;
 215         }
 216
 217         return true;
 218
 219  cancel:
 220         if (share_db->transaction_cancel(share_db)) {
 221                 smb_panic("transaction_cancel failed");
 222         }
 223
 224         return false;
 225 }
 226
 227 /*******************************************************************
 228  Fake up a Everyone, default access as a default.
 229  def_access is a GENERIC_XXX access mode.
 230  ********************************************************************/
 231
 232 struct security_descriptor *get_share_security_default( TALLOC_CTX *ctx, size_t *psize, uint32 def_access)
 233 {
 234         uint32_t sa;
 235         struct security_ace ace;
 236         struct security_acl *psa = NULL;
 237         struct security_descriptor *psd = NULL;
 238         uint32 spec_access = def_access;
 239
 240         se_map_generic(&spec_access, &file_generic_mapping);
 241
 242         sa = (def_access | spec_access );
 243         init_sec_ace(&ace, &global_sid_World, SEC_ACE_TYPE_ACCESS_ALLOWED, sa, 0);
 244
 245         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, 1, &ace)) != NULL) {
 246                 psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 247                                     SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 248                                     psa, psize);
 249         }
 250
 251         if (!psd) {
 252                 DEBUG(0,("get_share_security: Failed to make SEC_DESC.\n"));
 253                 return NULL;
 254         }
 255
 256         return psd;
 257 }
 258
 259 /*******************************************************************
 260  Pull a security descriptor from the share tdb.
 261  ********************************************************************/
 262
 263 struct security_descriptor *get_share_security( TALLOC_CTX *ctx, const char *servicename,
 264                               size_t *psize)
 265 {
 266         char *key;
 267         struct security_descriptor *psd = NULL;
 268         TDB_DATA data;
 269         char *c_servicename = canonicalize_servicename(talloc_tos(), servicename);
 270         NTSTATUS status;
 271
 272         if (!c_servicename) {
 273                 return NULL;
 274         }
 275
 276         if (!share_info_db_init()) {
 277                 TALLOC_FREE(c_servicename);
 278                 return NULL;
 279         }
 280
 281         if (!(key = talloc_asprintf(ctx, SHARE_SECURITY_DB_KEY_PREFIX_STR "%s", c_servicename))) {
 282                 TALLOC_FREE(c_servicename);
 283                 DEBUG(0, ("talloc_asprintf failed\n"));
 284                 return NULL;
 285         }
 286
 287         TALLOC_FREE(c_servicename);
 288
 289         data = dbwrap_fetch_bystring(share_db, talloc_tos(), key);
 290
 291         TALLOC_FREE(key);
 292
 293         if (data.dptr == NULL) {
 294                 return get_share_security_default(ctx, psize,
 295                                                   GENERIC_ALL_ACCESS);
 296         }
 297
 298         status = unmarshall_sec_desc(ctx, data.dptr, data.dsize, &psd);
 299
 300         TALLOC_FREE(data.dptr);
 301
 302         if (!NT_STATUS_IS_OK(status)) {
 303                 DEBUG(0, ("unmarshall_sec_desc failed: %s\n",
 304                           nt_errstr(status)));
 305                 return get_share_security_default(ctx, psize,
 306                                                   GENERIC_ALL_ACCESS);
 307         }
 308
 309         if (psd) {
 310                 *psize = ndr_size_security_descriptor(psd, 0);
 311         } else {
 312                 return get_share_security_default(ctx, psize,
 313                                                   GENERIC_ALL_ACCESS);
 314         }
 315
 316         return psd;
 317 }
 318
 319 /*******************************************************************
 320  Store a security descriptor in the share db.
 321  ********************************************************************/
 322
 323 bool set_share_security(const char *share_name, struct security_descriptor *psd)
 324 {
 325         TALLOC_CTX *frame = talloc_stackframe();
 326         char *key;
 327         bool ret = False;
 328         TDB_DATA blob;
 329         NTSTATUS status;
 330         char *c_share_name = canonicalize_servicename(frame, share_name);
 331
 332         if (!c_share_name) {
 333                 goto out;
 334         }
 335
 336         if (!share_info_db_init()) {
 337                 goto out;
 338         }
 339
 340         status = marshall_sec_desc(frame, psd, &blob.dptr, &blob.dsize);
 341
 342         if (!NT_STATUS_IS_OK(status)) {
 343                 DEBUG(0, ("marshall_sec_desc failed: %s\n",
 344                           nt_errstr(status)));
 345                 goto out;
 346         }
 347
 348         if (!(key = talloc_asprintf(frame, SHARE_SECURITY_DB_KEY_PREFIX_STR "%s", c_share_name))) {
 349                 DEBUG(0, ("talloc_asprintf failed\n"));
 350                 goto out;
 351         }
 352
 353         status = dbwrap_trans_store(share_db, string_term_tdb_data(key), blob,
 354                                     TDB_REPLACE);
 355         if (!NT_STATUS_IS_OK(status)) {
 356                 DEBUG(1, ("set_share_security: Failed to store secdesc for "
 357                           "%s: %s\n", share_name, nt_errstr(status)));
 358                 goto out;
 359         }
 360
 361         DEBUG(5,("set_share_security: stored secdesc for %s\n", share_name ));
 362         ret = True;
 363
 364  out:
 365         TALLOC_FREE(frame);
 366         return ret;
 367 }
 368
 369 /*******************************************************************
 370  Delete a security descriptor.
 371 ********************************************************************/
 372
 373 bool delete_share_security(const char *servicename)
 374 {
 375         TDB_DATA kbuf;
 376         char *key;
 377         NTSTATUS status;
 378         char *c_servicename = canonicalize_servicename(talloc_tos(), servicename);
 379
 380         if (!c_servicename) {
 381                 return NULL;
 382         }
 383
 384         if (!share_info_db_init()) {
 385                 TALLOC_FREE(c_servicename);
 386                 return False;
 387         }
 388
 389         if (!(key = talloc_asprintf(talloc_tos(), SHARE_SECURITY_DB_KEY_PREFIX_STR "%s",
 390                                     c_servicename))) {
 391                 TALLOC_FREE(c_servicename);
 392                 return False;
 393         }
 394         kbuf = string_term_tdb_data(key);
 395
 396         status = dbwrap_trans_delete(share_db, kbuf);
 397         if (!NT_STATUS_IS_OK(status)) {
 398                 DEBUG(0, ("delete_share_security: Failed to delete entry for "
 399                           "share %s: %s\n", c_servicename, nt_errstr(status)));
 400                 TALLOC_FREE(c_servicename);
 401                 return False;
 402         }
 403
 404         TALLOC_FREE(c_servicename);
 405         return True;
 406 }
 407
 408 /*******************************************************************
 409  Can this user access with share with the required permissions ?
 410 ********************************************************************/
 411
 412 bool share_access_check(const struct security_token *token, const char *sharename,
 413                         uint32 desired_access)
 414 {
 415         uint32 granted;
 416         NTSTATUS status;
 417         struct security_descriptor *psd = NULL;
 418         size_t sd_size;
 419
 420         psd = get_share_security(talloc_tos(), sharename, &sd_size);
 421
 422         if (!psd) {
 423                 return True;
 424         }
 425
 426         status = se_access_check(psd, token, desired_access, &granted);
 427
 428         TALLOC_FREE(psd);
 429
 430         return NT_STATUS_IS_OK(status);
 431 }
 432
 433 /***************************************************************************
 434  Parse the contents of an acl string from a usershare file.
 435 ***************************************************************************/
 436
 437 bool parse_usershare_acl(TALLOC_CTX *ctx, const char *acl_str, struct security_descriptor **ppsd)
 438 {
 439         size_t s_size = 0;
 440         const char *pacl = acl_str;
 441         int num_aces = 0;
 442         struct security_ace *ace_list = NULL;
 443         struct security_acl *psa = NULL;
 444         struct security_descriptor *psd = NULL;
 445         size_t sd_size = 0;
 446         int i;
 447
 448         *ppsd = NULL;
 449
 450         /* If the acl string is blank return "Everyone:R" */
 451         if (!*acl_str) {
 452                 struct security_descriptor *default_psd = get_share_security_default(ctx, &s_size, GENERIC_READ_ACCESS);
 453                 if (!default_psd) {
 454                         return False;
 455                 }
 456                 *ppsd = default_psd;
 457                 return True;
 458         }
 459
 460         num_aces = 1;
 461
 462         /* Add the number of ',' characters to get the number of aces. */
 463         num_aces += count_chars(pacl,',');
 464
 465         ace_list = TALLOC_ARRAY(ctx, struct security_ace, num_aces);
 466         if (!ace_list) {
 467                 return False;
 468         }
 469
 470         for (i = 0; i < num_aces; i++) {
 471                 uint32_t sa;
 472                 uint32 g_access;
 473                 uint32 s_access;
 474                 struct dom_sid sid;
 475                 char *sidstr;
 476                 enum security_ace_type type = SEC_ACE_TYPE_ACCESS_ALLOWED;
 477
 478                 if (!next_token_talloc(ctx, &pacl, &sidstr, ":")) {
 479                         DEBUG(0,("parse_usershare_acl: malformed usershare acl looking "
 480                                 "for ':' in string '%s'\n", pacl));
 481                         return False;
 482                 }
 483
 484                 if (!string_to_sid(&sid, sidstr)) {
 485                         DEBUG(0,("parse_usershare_acl: failed to convert %s to sid.\n",
 486                                 sidstr ));
 487                         return False;
 488                 }
 489
 490                 switch (*pacl) {
 491                         case 'F': /* Full Control, ie. R+W */
 492                         case 'f': /* Full Control, ie. R+W */
 493                                 s_access = g_access = GENERIC_ALL_ACCESS;
 494                                 break;
 495                         case 'R': /* Read only. */
 496                         case 'r': /* Read only. */
 497                                 s_access = g_access = GENERIC_READ_ACCESS;
 498                                 break;
 499                         case 'D': /* Deny all to this SID. */
 500                         case 'd': /* Deny all to this SID. */
 501                                 type = SEC_ACE_TYPE_ACCESS_DENIED;
 502                                 s_access = g_access = GENERIC_ALL_ACCESS;
 503                                 break;
 504                         default:
 505                                 DEBUG(0,("parse_usershare_acl: unknown acl type at %s.\n",
 506                                         pacl ));
 507                                 return False;
 508                 }
 509
 510                 pacl++;
 511                 if (*pacl && *pacl != ',') {
 512                         DEBUG(0,("parse_usershare_acl: bad acl string at %s.\n",
 513                                 pacl ));
 514                         return False;
 515                 }
 516                 pacl++; /* Go past any ',' */
 517
 518                 se_map_generic(&s_access, &file_generic_mapping);
 519                 sa = (g_access | s_access);
 520                 init_sec_ace(&ace_list[i], &sid, type, sa, 0);
 521         }
 522
 523         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, num_aces, ace_list)) != NULL) {
 524                 psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 525                                     SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 526                                     psa, &sd_size);
 527         }
 528
 529         if (!psd) {
 530                 DEBUG(0,("parse_usershare_acl: Failed to make SEC_DESC.\n"));
 531                 return False;
 532         }
 533
 534         *ppsd = psd;
 535         return True;
 536 }